Certain areas of the United States have serious water problems due to the presence of dissolved gases and minerals. Hydrogen sulfide is one of the gases often contained in these waters and its presence renders domestic water unsuitable for consumption. Radon is another gas often trapped in water in some sections of the United States, and, if present in high concentrations, may be dangerous. Objectionable amounts of soluble iron compounds and soluble compounds of other metals such as manganese and strontium may also be present in these waters. These dissolved gases and minerals should be removed and/or oxidized in order to provide water of domestic quality.
Small levels of organic components, e.g., hydrocarbons, organic chlorides, etc., may also be present in domestic water. These organic components must be removed, not only for consumption purposes, but also in instances where environmental contamination must be alleviated.
A variety of liquid treatment processes have been developed involving the aeration of such liquids by contact with an oxygen containing gas to remove the objectionable gases from the liquid as well as oxidize any mineral salts to a relatively innocuous and unobjectionable forms or convert such salts to precipitates which may be filtered prior to use. Radon also has been effectively removed from aqueous streams by aeration. Organic components have been oxidized or stripped from the aqueous medium via aeration. Representative prior art processes disclosing the treatment of water via aeration for the purpose of providing domestic water free of objectionable gases, mineral salts, radon and organic contaminants are as follows:
U.S. Pat. No. 2,872,415 discloses a domestic water treatment process for removing hydrogen sulfide and water soluble mineral salts such as iron, manganese and strontium by contacting the water with air. In principle, the water is first atomized at atmospheric pressure via a spinning disk atomizer wherein it is violently mixed with a controlled stream of air. This mixture then is impinged against a barrier to enhance atomization and substantial oxidation of the water as it passes through the unit. Complete gas elimination is effected. The oxygen-saturated water is delivered to a detention tank which is exposed to the atmosphere and held for a short period of time, e.g., 20 to 60 minutes. Prior to use, the water is filtered for delivery to the household.
U.S. Pat. No. 2,591,134 discloses an apparatus for the aeration of liquids, and particularly water, suitable for the removal of undesirable gaseous components such as hydrogen sulfide. The apparatus consists of a shell having a water inlet and outlet and means for controlling the level of water in the shell. Aeration is effected by passing the water through a spray nozzle in communication with an upwardly opening venturi tube for producing a cone shaped spray of water. The spray is directed against a horizontally disposed baffle plate having a depending edge flange formed into a cone-shaped central part. Aeration of the water stream is effected by introducing air from the outside via a duct to the venturi tube. Violent mixing of the cone shaped spray of water and air is effected by the impingement of the spray against the horizontally disposed baffle plate. The resultant water mist then falls downwardly and collects in the bottom of the shell therein for subsequent use.
U.S. Pat. No. 2,495,937 discloses a water treatment process and apparatus for the stabilization and sterilization of water. The patent suggests that it has long been known to use softeners and filters, as well as aeration, to remove gases which are in solution in underground water, such gases including carbon dioxide, hydrogen sulfide, methane, etc. The patent also disclosing a process for the stabilization of treated water via chlorination, chlorination being effected subsequent to aeration in order to minimize chlorine losses to the atmosphere. The process involves withdrawing water from a bottom portion of a large pool of water in an elevated position, dividing the water stream into major and minor streams and forcing both major and minor streams toward an upper portion of the pool. Aeration is effected on the major stream and chemical treatment is effected on the minor stream.
U.S. Pat. No. 2,590,431 discloses a water aerator and filter system suited for removing objectionable gases such as carbon dioxide and hydrogen sulfide therefrom. The aeration device consists of a tank having agitation means therein, the agitation means having apertures to enhance aeration of the water. Water level within the tank is controlled by a flow control switch. Noxious vapors are vented to the atmosphere.
U.S. Pat. No. 3,151,064 discloses a water conditioning method for removing unpleasant odors and improving the taste via aeration. Aeration is effected by means of horizontally disposed nozzles having a plurality of small outlet passages oriented relative to each other so that water and gases discharged therefrom impinge against each other causing atomization of the water. The intercepting water streams break up into individual water droplets and assist the gas stream in dispersing the spray by creating a high degree of turbulence. The water droplets fall into the tank and are held for subsequent delivery to the user.
U.S. Pat. No. 4,869,832 discloses a radon removal system incorporating a packed mass transfer aeration column sized to fit a single story residential building. Air is blown upwardly through the column and comes in contact with radon-laden water. On contact the air forces the radon out of the water. The radon-laden air is removed from the top of the column and vented to the atmosphere. The treated water then is transferred to a storage tank for subsequent use.
U.S. Pat. No. 2,088,691 discloses a gas liquid contacting apparatus of a type similar to that previously described in U.S. Pat. No. 2,591,134. In operation, liquid is forced through a liquid jet at high velocity through a chamber having a double cone or venturi-like throat wherein it is caused to impinge against a deflector having a cone shaped protrusion. The periphery of the deflector has coaxially disposed serrated rings or skirts. Aeration is effected by introducing air into the venturi-like chamber via air inlets disposed below the liquid jet. The serrated rings are suited for the purpose of further breaking up the liquid stream.